In a firearm, the sear is the part of the trigger mechanism that holds the hammer, striker or bolt securely until the right amount of pressure has been applied to the trigger when a shooter is ready to fire (trigger break). When enough pressure has been applied to the trigger, the sear releases the firing mechanism. The sear directly influences the “feel” and length or travel of the trigger pull. While a professional shooter may be able to proficiently use many weapons with differing trigger “feel” and pull, it has been demonstrated that novice shooters and professional shooters alike benefit from a short trigger travel and a crisp feeling trigger break.
Specific to pistols, the travel and tactile satisfaction or “feel” of the trigger can have a great impact on a shooter's sight picture and shot placement due to the relatively unsupported posture in a standard shooting stance. In a standard pistol shooting stance, the weapon is being mainly supported by the shooters hands around the grip of the pistol and minimal skeletal support. Whereas, a standard rifle or shotgun shooting stance allows a forward support provided by an extended arm, mid support around the grip of the rifle or shotgun, and rear support provided by the shoulder, creating an inherently more stable shooting position. Additionally, the type of trigger on a pistol can significantly impact the stability of the pistol during the trigger pull, and thus the sight picture and shot placement. The 1911-style trigger constrains the movement of the trigger pull to one axis which is parallel to the bore and prevents the introduction of unintended movement which would disrupt a shooter's sight picture. Conversely, a rotational style trigger requires both translation and rotation about a pivot to actuate and induces off-axis movement on the pistol. This is not a desirable feature as it introduces movement that might cause the shooter's sight picture to shift. The conclusion is that the travel and “feel” of the trigger, along with the direction of force during the trigger pull has a great impact on maintaining a good sight picture and a precise shot placement on a pistol platform.
Multiple pistol sear designs have attempted to create a “crisp” sear release while maintaining a positive sear engagement. A positive sear engagement disallows the ability for the sear to be disengaged other than by pulling the trigger. While many pistol designs have been created with longer and heavier trigger pulls, the designs with short, “crisp” trigger pulls have had more commercial success and a larger shooter demand due to the behavior of the sear. Two such pistols are the 1911 and the Glock™.
The 1911 is a hammer-fired pistol which uses a translational trigger that pulls straight back, which distinguishes it from a rotational trigger. Precise machined angles between the sear and the hammer, in additional to the single axis translational trigger, are what influence the crisp “feel” of the trigger pull. The Glock™ is a striker-fired pistol. A ledge directly between the sear and the striker, as well as the rotational style trigger, determine the “feel” of the trigger pull. Both the 1911 and the Glock™ maintain a positive sear engagement while the respective hammer and striker are held back in the battery ready to fire position.
Both designs have certain drawbacks. The sear of the 1911 is under constant pressure by the hammer. This means that any imperfection in the machining of the engagement ledges between the sear and the hammer may lead to a negative sear engagement and an accidental discharge. The 1911 design accounts for this by the incorporating quality control checks during manufacturing and the inclusion of two manual safeties, and in later designs an additional passive safety. The drawback is that due to the design of the interaction of the sear and the hammer, if strict quality control is not maintained through high volumes of production, it is possible for the occurrence of negative sear engagement. This design, however, along with the single axis translational trigger, does allow for a short, crisp trigger pull.
In the Glock™ design, a rotational trigger translates the movement from the trigger pull to the trigger bar, allowing the sear, which is a geometry on the back of the trigger bar, to release the striker. The drawback of the Glock™ design is that it has an inherently long trigger pull due to the translational connections within the trigger and sear assembly, and the inclusion of a rotational trigger. Unlike the 1911, the Glock™'s sear design is not at risk of quality control issues leading to the possibility of negative sear engagement; however, the inclusion of two passive safeties in addition to the sear itself, lends undesirable effects on the trigger “feel”.
There is an unmet need, therefore, for a sear design that allows for a short trigger pull, a crisp trigger “feel”, and has an inherently or intentionally positive sear engagement regardless of production volume or quality control.